During the marketing process of goods, in order to attract customers, the merchants usually display the goods in the display cabinets and use lamplight to illuminate them, in order to highlight the characteristics of the goods, or use light boxes for advertising. Usually lamplight is used to illuminate the goods in the display cabinets or the light boxes. With the development of LED technology, people more and more frequently use LED light sources to replace the traditional illumination devices. However, due to the characteristics of the LED light sources, it is necessary to perform secondary optical processing on the light emitted by them, then it is necessary to equip them with an optical lens, so as to meet the illumination requirements of the light boxes.
A light box usually comprises a bottom surface, a top surface arranged to be opposite to the bottom surface, and a plurality of side surfaces connected between the bottom surface and the top surface, wherein the lens is arranged on the bottom surface, thereby causing the light from the light source to illuminate, after the secondary optical processing by the lens, the top surface and the side surfaces. However, as is known to all, usually no advertising characters or patterns are arranged on the top surface of the light box. Thus, there is no need to illuminate the region of the top surface. The traditional lens cannot avoid illuminating this region, resulting in unnecessary light loss.